1. Field of the Invention
The present invention relates generally to a base for wire bond checking and more particularly to a base having an upper surface which arranges a probe thereon serving for wire bond checking.
2. Description of the Related Art
In recent years, as the function of IC becomes complicated, there exists a need in the development of packing for an improved high density lead frame. BGA (Ball Grid Array) packages of the electronic and computer industries have been required to support higher lead counts within the same package footprint area. Lift bonds or missing wires or bonding pads polluted with compound result in an open loop of the BGA package that causes the BGA package to fail to work. Conventional wire bonding systems, without checking wire bonding, cannot stop bonding immediately and open loops occur during wire bonding. So the wire bond system still continues to use unnecessary wire bonds that increase the cost of product.
U.S. Pat. No. 5,712,570, issued on Jan. 27, 1998 to Heo et al., discloses a method for checking the wire bond of a semiconductor package. An electroconductive metal layer of gold or copper is grounded on a chip-bonding portion of a PCB (Printed Circuit Board) of the BGA package as well as on a passage extending between the chip bonding portion and the mold gate of the PCB. After the wire-bonding step, a probe and capillary of a wire bond checking system contact the mold gate and a semiconductor chip, respectively. Then, a current is sent to the BGA package from the checking system to check whether the wire bond is closed or not. When there is neither a lift bond nor a missing wire in the BGA package, the wire will transmit the current. However, the probe of the wire bond checking system needs to move to the ground of the upper surface of the substrate. Then, the probe goes down to the substrate and aims at the ground of the upper surface of the substrate for wire bond checking.
The present invention intends to provide a base having a probe which is arranged on the surface thereof for contacting the ground of the substrate and is also electrically connected with wire bond checking system. In addition, the probe is elastically attached to the base and contacts the ball pads of the lower surface of the substrate for wire bond checking before wire bonding. The probe contacts the ball pads of the lower surface of the substrate for wire bond checking while the substrate is placed on the base, so that the present invention reduces the steps of the probe aiming at the ground of the substrate of U.S. Pat. No. 5,712,570. The present invention needs not aim the probe at the ground since the probe contacts the ball pads of the lower surface of the substrate for wire bond checking while the substrate is placed on the base.